Thank you for contacting us. We are happy to help guide you, but can be difficult for us to troubleshoot problem when we have not been working on/building the actual site. This is because every website can be customized differently.
When I look at your website, I get a blank page, this usually means there is an error being suppressed. I first recommend enabling error reporting
in PrestaShop, which should allow the error to display.
Let us know what the errors are and we can help work through them.
What Arnel is suggesting, is downloading the same version of PrestaShop you are running, and uploading it, then reinstalling it manually
with your existing database.
As per TJ's previous comment, there may be a missing table in your existing database. In this case you will most likely have to restore from one of your backups.